A typical liquid crystal display device is equipped with two polarizing plates disposed in such a manner that a liquid crystal layer lies between them. The two polarizing plates are arranged so that the direction of polarization of the light is at right angles to one another. The two polarizing plates form a mechanism that controls ON/OFF (transmittance and blocking) of the light emitted from a backlight in accordance with a change of liquid-crystal molecular orientation by application of voltage. Such polarizing plates have a configuration that a polarizer is sandwiched with polarizing plate protective films such as a cellulose acylate film. The polarizer is made of a material which is a polyvinyl alcohol (PVA) crosslinked by iodine. Especially, a cellulose acylate film is favorably used for a polarizing plate protective film because of its excellent transparency and small haze.
Meanwhile, recently, inclination for large-size-screen, enhancement in the quality of image, and price reduction of the liquid crystal display device are progressing with a focus on application to TV. A demand for technology development addressing such progress is more and more increasing. It is expected for frequency of outdoor use to increase with a focus on application to digital signage or a variety of portable devices and the like in future. There is a demand for development of a liquid crystal display device that can be used even under harsher conditions than in the past and that is capable of realizing high quality image. In view of such needs, it has been pointed out that when the above-described polarizing plate is used under environment of high temperature and high humidity, display unevenness is apt to generate. The display unevenness is thought to be caused by the mechanism in which a stress resulting from shrinkage of the polarizer under conditions of high temperature and high humidity is introduced into a polarizing plate protective film whereby a change of a phase difference of the polarizing plate protective film occurs near the frame fixing the polarizing plate.
While on the other hand, addition of an acrylic resin to a cellulose ester film is proposed in order to suppress generation of depositions or the like at the time of production, and to reduce both retention and water-vapor transmission ratio (see Patent Literature 1). Further, in order to suppress humidity fluctuation of phase-difference value, there is an example of application of a compound having a furanose structure or a pyranose structure to the cellulose derivatives (see Patent Literature 2).